(1) Field of the Invention
The present invention relates to a paper discharge structure and an image forming apparatus, in particular relating to a paper discharge structure whereby a recording medium with an image formed thereon by an electrophotographic process is discharged onto a paper output tray by means of paper discharge rollers, as well as relating to an image forming apparatus using the structure.
(2) Description of the Prior Art
Conventionally, in the paper discharge structure used in an image forming apparatus such as a copier, scanner device, facsimile machine, etc., the output sheets are usually discharged onto a paper output tray. The stacking performance of the sheets discharged on this paper output tray is one of the important factors for the user to achieve their task efficiently.
Specifically, the point is whether the user is able to obtain discharged sheets in an organized manner as they are just taken out from the output tray or the user needs to tidy up the stack of discharged sheets once again after they are taken out. That is, there is a demand for a paper discharge structure that provides user-friendly stacking performance of discharged sheets.
On the other hand, in recent years image forming apparatuses have been enhanced in speed, and also so-called multi-functional machines having multiple functions have been developed and put into practical use. These high-speed machines as well as multi-functional machines are also demanded to be compact without bulkiness. As a result the space given for the paper discharge structure has become designed to be small.
To achieve this it is necessary to reduce the volume of the paper discharge structure. However, this entails degradation of the stacking performance of discharged paper on the paper output tray.
To deal with this, as a conventional technology there has been a proposal of a sheet handling apparatus for discharging sheets onto a paper output tray with its stacking performance improved by increasing or decreasing the discharging speed of sheets without drastically changing the apparatus configuration (see Japanese Patent Application Laid-open 2000-118824).
However, since this scheme needs to increase and decrease the speed of sheet output, there is a fear that it is impossible to achieve a desired number of outputs for supporting recent high-speed configurations.
Further, when a large amount of sheets are output, the discharged sheets of paper fall at different positions, so that the stacked conditions of individual sheets are diversified, causing the rear ends of sheets to be stacked uneven. As a result, in some cases there is a risk that a designated amount of sheets cannot be accommodated because the output sheets lean against the wall of the paper discharge portion. To avoid this, it is necessary to discharge paper at a suitable position by controlling the speed of discharging the paper, and this in turn causes the problem in that the speed control of paper discharge is complicated and stable output speed cannot be obtained.